Denison’s Phoenix ISR uranium mine: design, capex and schedule notes for engineers
Reviewed by Joe Ashwell
First reported on MINING.com
30 Second Briefing
Denison Mines has started full construction of the C$700 million Phoenix in-situ recovery uranium project in northern Saskatchewan, installing the first perimeter freeze wall after completing more than 20% of civil works and nearly all ground preparation for the processing plant and wellfield. The Athabasca Basin’s first commercial ISR mine is targeting mid-2028 first production, peak output of about 9 million lb U3O8 per year over a 10-year mine plan, drawing on 56.7 million lb of proven and probable reserves grading 11.7% U3O8. Key infrastructure includes a new 138 kV SaskPower transmission line, on-site concrete batch plant, quarry, expanded 400-person camp and an airstrip under preparation, with engineering about 90% complete.
Technical Brief
- First perimeter freeze wall is being installed to hydraulically isolate the initial ISR mining zone.
- Over 20% of civil works are complete, with nearly all plant and wellfield ground prep finished.
- Concrete pours for processing plant and main power transformer foundations are scheduled to start next month.
- A concrete batch plant and nearby quarry are on site, supplying aggregate and ready-mix for foundations.
- SaskPower’s 138 kV transmission line to Phoenix is complete, enabling grid power for construction and operations.
- Temporary camp capacity has been expanded to nearly 400 personnel, with an airstrip currently under preparation.
- Engineering is ~90% complete, with 95% of main design packages already issued for construction.
- 2023 feasibility (updated 2024) reports post-tax NPV8 of C$1.57 billion and 73% IRR.
- Average all-in operating cost is estimated at C$18.41/lb U3O8 over the 10-year mine plan.
- Denison controls 95% of Wheeler River (90% direct, 5% via JCU), enabling shared infrastructure with the Gryphon underground project.
Our Take
With Phoenix’s post-tax NPV of C$1.57 billion against a C$700 million capex and a 73% IRR, Denison Mines sits at the very top end of project economics in our uranium coverage, which is likely to pressure higher-cost Athabasca Basin developments to rethink sequencing or scale.
Denison’s C$418 million cash position plus C$216 million of U3O8 inventory at Phoenix gives it unusually strong pre-production liquidity compared with other uranium developers in our database, reducing reliance on dilutive equity or high-cost debt during the two-year build.
The 138 kV SaskPower line highlighted in the January 2026 related piece, combined with Phoenix’s ISR design, positions this Athabasca Basin project to market itself as a relatively low-carbon uranium source at a time when around 30 countries are targeting a tripling of nuclear capacity by 2050.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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